Process for preparing filamentary microtapes of labyrinthian cross section



F. PHILLIPS PROCESS FOR PREP N ILAMENT OF LABYRINTHI CROSS S Filed Feb. 4, 1966 3,356,783 MICROTAPBS c ION INVENTOR. Free A PAH/1,22;

Patented Dec. 5, 1967 ABS :2! CT OF THE DISCLOS This invention involves a method for preparing filamentary microtapes of folded cross section by passing a flat flexible unfolded tape of a thermoplastic polymer into a moving heated shaping device in such a manner as to provide only lateral shaping forces against the tape followed by the removal of the tape from the device and subsequently cooling the so formed filamentary microtape.

This application is a continuation-in-part of U.S. Ser. No. 258,661, filed Feb. 1, 1963, now abandoned, which was a continuation-in-part of U.S. Ser. No. 30,247, filed May 19, 1960, now abandoned.

.This invention relates to a process for preparing filamentary microtapes of labyrinthian cross section from fiat tapes and ribbons. More particularly, it relates to such a process which provides exceptional control of the width, denier, and cross-sectional configuration of said microtapes.

For many applications and uses, it is desirable to have filamentary articles of other than the traditional solid cylindrical configuration. For example, flat tapes and ribbons would seem to be a suitable form for the manufacture of many woven and unwoven fabrics and similar articles. Such tapes and ribbons provide unusually high covering power per unit of volume and thus result in fabrics of less weight and of greater flexibility than those fabrics prepared from the prior lamentary articles of cylindrical section. However, when tapes or ribbons are employed in the usual weaving operations, it is usually necessary to twist, to plait, or otherwise to change the character of the fiat tape or ribbon prior to weaving. Those operations result in a filamentary article which ischaracterized by poor control of width, denier, and cross-sectional geometry and result in fabrics having a hand that is little better than those prepared from the conventional cylindrical filaments.

One filamentary article that is finding increasingly wide usage in many applications is a filamentary microtape that is essentially rectangular, oval, or elliptical in peripheral silhouette. In cross section, however, these useful microtapes consist of a continuous transverse section of a tape or ribbon having the edges curled or having a transverse section of the tape or ribbon folded two, three, or more times back upon itself resulting, in effect, in a series of layers separated by air. This curling or folding results in a microtape having a labyrinthian cross section. These microtapes of such labyrinthian section may be ,used directly in conventional textile operations and, when so used, are characterized in providing the high covering power per unit of volume inherent in such peripheral silhouette. In addition, these microtapes are relatively bulky due to the air spaces between the layers.

These filamentary microtapes of labyrinthian cross section, when prepared from the known organic thermoplas tic resinous materials, are of great desirability for several reasons, in addition to those just mentioned. Tapes and ribbons from which the desired microtape may be formed are readily prepared. Thermoplastic microtapes permit the preparation of fabrics which may be thermally formed, heat sealed, embossed, calendered, and the like. However, the thermoplastic materials frequently require orientation if the optimum properties are to be achieved in the filamentary article. In many cases it is necessary or at least desirable to the very attainment of the tape or ribbon to orient the tape or ribbon to. fabrication. However, the

oriented form of a polymer is subject to certain difficulties, such as fibrillation in flat tape form, when that flat tape is subjected to great stress. It would be desirable to have a process for preparing oriented filamentary microtapes of Iabyn'nthian cross section from continuous, coherent tapes and ribbons.

A method for preparing such microtapes is disclosed in U.S. Patent 2,858,186, issued Oct. 28, 1958, on an application filed by J. R. Frost. In that patent there is disclosed a process wherein a latex of a polymer is continuously coagulated, the so-formed coagulum slit into fiat tapes, the slit tapes dried, fused, shaped, and oriented. However, reliance solely on an inherent tendency to curl or to fold, as in that patent, results in filamentary microtapes of wide width variation. In addition, such reliance depends to a very great extent on the polymer and latex properties and characteristics. Thus, reproducibility of width, bulk density, cross-sectional configuration, and other properties requires in the first instance essentially constant latex and polymer properties and characteristics. However, to reproduce a latex with such exactitude is, in the practical sense, extremely difiicult to accomplishi iIt would be desirable to have a process or method for preparing such microtapes, which process was less dependent on the characteristics of the latex and the polymer properties for the filamentary geometry than with prior known processes.

Accordingly, it is the principal object of this invention to provide a process for preparing filamentary microtapes of labyrinthian cross section, which process provides substantially rigid and exact control of the microtape width and denier.

It is a further object of the invention to provide such a method utilizing a microporous tape whereby the tapeis shaped and fused essentially simultaneously.

Another object is the provision of such a method utilizing a tape or ribbon of an organic, thermoplastic material.

The above and related objects are achieved by the method comprising (1) the passage of a fiat, flexible tape of an organic thermoplastic polymer into heated restricting means of narrower width than said tape, while said tape is under substantially no longitudinal stress, said tape being retained in said restricting means until said tape has attained the desired cross-sectional configuration, said heated restricting means being of different shape than the ultimate configuration of the produced filamentary microtape, said tape being passed into said heated restricting means in such a manner that the longitudinal axis of said tape is centered in said restricting means, and (2) removing the shaped tape from said restricting means, followed by (3) cooling the so-formed filamentary microtape.

The tapes useful in the present method may be of any organic thermoplastic resinous material. Materials which may be advantageously used are the normally crystalline polymeric materials. These are the polymers which have a tendency to form crystallites or sites where small segments of a plurality of the polymer'chains are oriented and held in position by secondary valence forces. This crystallite formation or crystallinity is usually visible when the polymers are examinedby X-ray diffraction.

Typical of the normally crystalline polymeric materials falling within the advantageous definition are the polymers and copolymers of at least 70 percent by weight of vinylidene chloride with the remainder composed of one or more other monoethylenically unsaturated comonomers exemplary of which are vinyl chloride, vinyl acetate, vinyl propionate, acrylonitrile, alkyl and aralkyl acrylates having alkyl and aralkylgroups of up to about 8 carbon atoms, acrylic acid, acrylamide, vinyl alkyl ethers, vinyl alkyl ketones, acrolein, allyl esters and ethers, buta'rliene and chloroprene. Known ternary compositions alsomay be employed advantageously. Representative of such polymers are those composed of at least 70 percent by weight of vinylidene chloride with the remainder made up of, for example, acrolein and vinyl chloride, acrylic acid and acrylonitrile, alkyl acrylates and alkyl methacrylates, acrylonitrile and butadiene, acrylonitrile and itaconic acid, acrylonitrile and vinyl acetate, vinyl propionate or vinyl chloride, allyl esters or ethers and vinyl chloride, butadiene and vinyl acetate, vinyl propionate or vinyl chloride, and vinyl ethers and vinyl chloride. Quaternary polymers of similar monomer composition will also be known. It has been found that the normally crystalline copolymers composed of from about 92 to 99 percent by weight of vinylidene chloride and correspondingly from 8 to 1 percent by weight of acrylonitrile or of a lower alkyl acrylate have suitable polymerization characteristics, are well adapted for use in the manipulative steps in this process, and result in exceptionally useful filamentary articles. For these reasons, these vinylidene chlorideacrylonitrile and vinylidene chloride-lower alkyl acrylate copolymers represent preferred species for use herein. It should be understood, however, that the process is not limited to the treatment 'of tapes and ribbons of normally crystalline polymers but that those formed from any non-elastic, polymeric material may be used. There are many materials, such as polyvinyl chloride and polystyrene, Which are capable of forming continuous, coherentarticles, which are orientable, but do not normally form crystallitcs. The polymeric materials, whether crystalline or non-crystalline, may also include minor amounts of monomers, such as vinyl pyrrolidone, vinyl oxazolidinone, vinyl alkyl oxazolidinone, and the like, which are known to aid the dye-receptivity and other properties. of fibrous materials. Likewise, polymers containing interpolymerized light and heat stabilizersmay be used. Also operable in the present method are tapes and ribbons of polymeric materials, such as the polyolefins, including, for example, polyethylene, polypropylene, copolymers of ethylene and propylene, and polyisobutylene. Equally useful in tke method are the tapes and ribbons formed from condensation polymers, such as the polyamides, including polyhexamethylene, diadipamide, and the polyesters, including polyethyleneterephthalate..The limitation then on the material of which the tapes are made include thermoplasticity and an ability to be formed into a fiat tape or ribbon.

The useful tapes for the present method are flexible tapes usually of about 0.001 to 0.005 inch in thickness and of about 0.1 to 1 inch in width. The thickness and width to be used in any given instance will depend in large measure upon the end product desired. The above limits are those which would normally be associated with the manufacture of filamentary microtapes finding their way into the textile art. When it is desired to make filamentary microtapes of greater size than, for example, about 0.3 inch, it would usually be found desirable to employ other known fabrication means, such as thermal extrusion, for their preparation. Wide sections .of tape, which are more accurately referred to as films, are not handled conveniently in the present procedural steps. However, it should be understood that the process is not limited precisely to the l-inch maximum, since useful articles may be prepared herefrom, although usually with passes is narrower than the flat tape tudinal stress should be only such a less control of width and cross-sectional configuration than with the narrower tapes.

The tapes and ribbons finding use in the present in-' vention are continuous but preferably unfused structures. By unfused is meant that the tape or ribbon is partially coalesced to have sufficient coherence to be self-supporting but requires thermal exposure above the temperature of plastic flow to attain that complete homogeneity of the fused article. Such continuous, unfused tapes and ribbons are preferred structures for use herein, because the method permits. and operates to greatest advantage with, simultaneous fusion and shaping. Such unfused tapes and ribbons frequently will have an inherent tendency to curl or to distort laterally under the influence of elevated temperaturc. The present process can make maximum use of that inherent tendency. Typical of such unfused structures are the coagula resulting from the continuous localized coagulation of a latex and the deposits resulting from the casting and drying of latex films. It should be apparent, however, that the method is also operable for preparing microtapes fromthose tapes and ribbons which are overtly fused to an extent which provides properties acceptable for the contemplated end use without further fusion. Thus, the method may be used with the thermal extrudates and other products of similar plastics fabrication techniques.

As mentioned, the method of the present invention involves the passage of a flat tape in planar fashion into confining and restricting means in a particular manner to cause the formation of the desired labyrinthian cross section. These restricting means are of smaller dimension than the width of the fiat tape passed therethrough. The confining and restricting means may take any given form wherein the cross-sectional area through which the tape itself. The restricting means will not have the shape or form of the ultimate microtape produced by the process, however. The process is not a molding technique. A particularly convenient and accordingly preferred means is a groove in the surface of a heated shaping device. With any given microtape the shape and dimensions of the groove determine in large measure the shape and final dimensions of the microtape. For example, with a groove geometry having divergent sides, such as those illustrated in FIG- URES l, 2, 3 and 4 of the appended drawings, the edges of the flat tape are caused to curl inwardly in a manner as will be described. Grooves having essentially parallel sides, such as illustrated in FIGURE 5 of the appended drawings, tend to cause a mechanical folding of the edges of the fiat tape. The particular geometry desired to achieve a given end product will be able to be easily determined by simple preliminary experiments.

The manner in which the tape or ribbon is shaped is also critical. While in the shaping or restricting means, the forces applied to the tape should be essentially completely lateral. The forces should be such that the edge portions of the tape will be rolled, folded, curled, or otherwise distorted from the original plane inwardly toward the longitudinal center of the ribbon. It should be apparent that a minimum amount of longitudinal tension must be applied to any flexible tape to maintain its planar in tegrity so that any lateral forces will be uniformly applied. However, for purposes of this invention, any longiminimum and not be of such magnitude as an orienting stress or similar force. This consideration is of most importance when the tape is a coagulum of a latex. Such a coagulum is weak and brittle and will break if any significant tensile stress is applied thereto.

The advantages and benefits, as well as the operation of the herein claimed method, will be more apparent from the following description and the appended drawings which illustrate a preferred procedural sequence for carrying out the method. In the drawings,

FIGURES 1-5 represent typical groove configurations finding use in the invention,

FIGURES 6-9 show the microtape in various stages of formation,

FIGURE 10 shows schematically a useful procedural sequence, and

FIGURE 11 is a plan view of a useful grooved roller.

In the embodiment illustrated in FIGURE 10, a flat tape I0 is fed through a suitable guide 11, around a first pair of snubbing rolls 12, into a groove cut into the periphery of a rotating roll or drum 13. Roll 13 may be driven or may be an idler roll. In any case, roll 13 should rotate in the same direction as and with about the same speed as the tape lit). The snub rolls 12 and grooved roll 13 are so disposed that the flat tape 10 preferably enters the groove tangentially with the center line of the tape 10 in register with the center line of the groove. The ape is caused to travel about the roll 13 and is taken oii tangentially by a second pair of snub rolls 14. After shaping, the microtape is passed about a third pair of snubbing rolls (not shown) operated at a greater peripheral speed than the second pair lid of snubbing rolls to cause orientation therein. The so-formed microtape is then passed to a suitable wind-up means (not shown), through other textile operations, or to any other desired point. The grooved roll 13 employed in the illustrated embodiment is a particularly convenient means for providing constant temperature, constant speed relative to the linear velocity of the tape, a relatively long length of travel in contact with the confining means, and is simple to construct and to change when a different end product is desired.

As earlier mentioned, the shape and relative size of the groove compared to the the tint tape determine to great extent the configuration of the resulting microtape, even though the shape of the groove does not correspond to the final configuration of that microtape. The sequence of stages that is passed through by the tape in a typical groove shape is shown in FIGURES 6 to 8. In FIGURE 6 there is shown a fiat tape just as it enters thegroove. In FIGURE 7 the edge curling has just started shortly after entering the groove. The final shaping exerted by the groove is shown in FIGURE 8 wherein it is noted that the width of the microtape conforms to the width of the flat portion of the groove. In this respect, it should be noted that the groove configurations having a flat root, such as in FIGURES 3 and 4, provide substantially better width and denier control than other configurations, such as those illustrated in FIGURES l and 2. As a result, the groove configurat'pns having a fiat root are to be preferred.

Also as earlier mentioned. when mechanical folding is to be desired, then a groove with parallel or substantially parallel sides has been found to be most useful. This tends to encourage the edge portions of the flat tape to be folded back upon itself, as illustrated in FIGURE 9.

It should be apparent that for the groove to accomplish its intended purpose there should be a force exerted downwardly toward the groove root on the tape to cause its descent into the root of the groove. With the preferred grooved roller, this downward force is inherent if the flat tape, while under constant minimum forwarding tension, is caused to enter tangentially and if the tape is caused to travel in an are so that the rise of the are between entering and take-off is greater than the depth of the groove. However, it should be appreciated that this is the minimum length of travel. The actual are that is traveled by the tape will depend upon the amount of shaping desired. the heat setting necessary, the polymer being used, and similar factors. This may be determined by simple preliminary adjustments. The materials of which the confining means, such as the grooved roll, are constructed should be non-thermoplastic and non-heat distortable with a surface providing a ready release of the tape. For the organic,'thermoplastic materials mentioned as finding utility in this invention, it has been found that a particularly desirable surface can be made of a steel grooved roll coated with solid polytetrafluoroethylene. Other materials will be suggested to the skilled worker. It should be understood that the invention is not limited to a grooved roll but that obvious mechanical equivalents, such as grooved continuous belts, may also be used.

As mentioned, the method of the present invention permits simultaneous fusion, shaping, and heat setting of the cross-sectional configuration. The heat used in the present method must be sufiicient to fuse the tape. Thus, temperatures at which plastic flow of the polymer under the forces inherent in the process are required. These temperatures are characteristic of each polymer and will be known. The amount of heat needed in any given instance will depend in large measure on the material of which the tape is composed, the thickness and width of the tape, and the end product desired. Some polymers have higher softening temperatures than other polymers and, consequently, require a greater heat input for fusion or other thermally dependent treatment. Also, the amount of heat required to heat set a given configuration will vary with the cross-sectional geometry involved. When a grooved roll is used for a shaping device, it is most convenient to introduce heat transfer fluids through the trunnions of the roll itself. If desired, auxiliary heating means, such as radiant heaters mounted opposite the grooved roll may be employed.

The present method results in several benefits. It is capable of continuous operation. The method produces a higher tenacity tape than those obtained by other methods and the present method produces a tape of more uniform width than that obtainable by unrestrained curling as by a thermal treatment without the restricting means.

It should be apparent that reproducibility of the folding is obtained only when the dimensions of the fused, fiat tape are essentially constant and the shaping conditions, such as the level at which the tape enters the groove, the depth to which it travels within the groove, and other factors, are maintained substantially constant. These'constarlt conditions are easily attained by maintaining substantially constant minimum forwardly tension during the fusing and shaping steps.-This minimum forwarding tension is attained with the second set of snubbing rolls and by having the restricting means travel at the same relative speed as the tape.

As mentioned, the process of the present invention permits the preparation of the microtapes from unfused, unoriented tapes or ribbons. This process results in several benefits. It is capable of continuous operation and is capable of being fitted into an integrated scheme that would include the tape or ribbon-making procedural sequence immediately preceding the present process. The rnicrotapes resulting from the process of this invention are characterized by a higher tenacity and a better hand than the fiat tapes or ribbons formed from the same polymeric materials. The microtapes are further characterized by uniform width and denier and by the absence of any frayed, uneven, or torn edges.

By means of the present method and apparatus, it is possible to prepare microtapes of a wide variation in width/thickness ratio. Thus, microtapes-having a width which is about two times greater than its thickness may be prepared with little deviation in this ratio. Such a filament will approximate the known monofilaments and fibers of oval cross section. However, with the same apparatus and with minor change in conditions, the width/ thickness ratio may be changed to 10 to 1 or greater. By merely changing the groove size, it is possible to attain width/thickness ratios of 30 to l or higher. Microtapes of such width/thickness ratios closely approximate fine ribbons or tapes and yet are subject to unusually exact control of width and denier and have edges which are non-frayable and have high tear strength.

change in apparatus and conditions. When two or more.

fiat tapes or ribbons are stacked and passed through the herein claimed procedural sequence, there results a microtape of similar configuration to that of a single tape but with proportionately increased thickness and denier. The width of the so-laminated orplied tapes is relatively modestly increased over that of the single, flat tape.

It will be appreciated that width/thickness ratios, denier, and cross-sectional configuration may be influenced by tape width and thickness, as well as the above-mentioned factors. The tape width can be adjusted with the slitting means. Tape thickness can be varied during its preparation or by the aforementioned plying techniques.

It can thus be seen that the process is susceptible in flexibility of operation to a diversity of microtape crosssectional configurations, deniers, and width/thickness ratios without the major retooling required by the prior known filament-making process when any change is contemplated.

The operation of the method will be more apparent from the following illustrative examples wherein all parts and percentages are by weight. 1

Example I A tape prepared by the continuous coagulation of a latex of a copolymer of 97 percent vinylidene chloride and 3 percent acrylonitrile and which was 0.0025 inch' of 180 C. The tape was fed onto the drum tangentially at a speed of approximately 50 feet per minute. The drum was rotated at a surface speed of about 50.5 feet per minute. A pair of water-cooled snub rolls removed the microtapes from the drum at a speed of 54 feet per minute. After cooling, the microtapes were passed about another set of snubbing rolls operated at a peripheral speed to impose a stretch ratio of 4 to 1 on the microtape. The fiat tapes, as prepared, were characterized in having a porosity gradient from one surface to the other and in the present run the tapes were positioned so thatthe more dense side was toward the fusion drum. The tape was caused to travel around the drum for about 24, inches, The resulting microtapes had a configuration of the edge portions rolled over into a spiral section and the center portion of the tape then folded over so that the curled edge portions were almost touching one another. The width of the microtapes was about 32.75 mils. The standard deviation in width was 3.44 mils so thatthe coefficient of variation of the width was about 10.5 percent.

By way of contrast, the fiat tapes, when fused without folding or rolling, were found to vary in width from about 30 to about 80 mils giving a coefiicient of variation of the widthof about 30 percent.

In a similar manner, four tapes were superposed on each other and passed through the procedural sequence. The result was a microtape of about 1600 denier which had a width of 0.047 inch, a thickness of 0.007 inch, and a width/thickness ratio of 6.7.

Example 2 A film was prepared as in Example 1 having a thickness of 0.003 inch which was slit into tapes having a width of 0.32 inch. The tapes were dried and passed onto a drum having a polytetrafiuoroethylene coating having V-shaped grooves in the surface inch deep by A inch wide at the roll surface. The tape was passed with the central longitudinal axis centered in the groove. The drum was maintained at 200 C. This fusion drum was run 1.2

times faster in peripheral speed than the snubbing rolls feeding the tapes onto the drum. After leaving the fusion drum, the tapes were passed around cooled snubber rolls driven 1.2 times faster than the fusion drum. The microtape was then stretched 4 to 1 over a third set of snubbing rolls. The result was a microtape which was 21 mils wide, about 6 mils thick, and of 550 denier. The configuration was such that the edge portions were rolled over until the spirals almost touched each other (similar to that shown in FIGURE 8). The width/thicl'ness denier and configurational control was exceptional.

What is claimed is:

1. A method for preparing filamentary microtapes of labyrinthian cross section comprising (1) the passageof a Hat, flexible tape of an organic thermoplastic polymer into a moving heated restricting means of narrower width than said tape while said tape is under substantially no longitudinal stress said restricting means moving in the direction of travel of said tape and at essentially the same peripheral speed as the linear speed of said tape so that the only shaping forces exerted on said tape are lateral forces, said tape being retained in said restricting means until said tape has attained the desired cross-sectional configuration, said heated restricting means being of different shape than the ultimate configuration of the produced filamentary microtape, said tape being passed into said heated restricting means in such a manner that the longitudinal axis of said tape is centered in said restricting means, and (2) removing the shaped tape from said restricting means, followed by (3) cooling the so-formed filamentary microtape.

2. The method claimed in claim 1 wherein said flat,

flexible tape is a microporous coagulum resulting from the continuous localized coagulation of a latex of a normally crystalline polymeric material and said restricting means is heated to the temperature of plastic flow of the poly mer wherein said coagulum is retained in said restricting means for a time sufficient for said coagulum to be completely fused and wherein the so-formed microtape is oriented following cooling.

3. The method claimed in claim 2 wherein said normally crystalline polymeric material is a normally crystalline vinylidene chloride polymer.

4. The method claimed in claim 3 wherein said normally crystalline vinylidene chloride polymer is a copolymer of at least 70 percent vinylidene chloride with the remainder of acrylonitrile.

5. The method claimed in claim 3 wherein said normally crystalline vinylidene chloride polymer is a copolymer of at least 70 percent vinylidene chloride with the remainder of a lower alkyl acrylate having from 1 to 8 carbon atoms in the alkyl group.

6. The method claimed in claim 1 wherein said flat, flexible tape is from 0.001 to 0.005 inch in thickness and from 0.1 to 1 inch in .width.

7. The method claimed in claim 1 wherein said organic, thermoplastic polymer is a solid polyolefin.

8. The method claimed in claim 7 wherein said solid polyolefin is polyethylene.-

9. The method claimed in claim 7 wherein said solid polyolefin is polypropylene.

References Cited UNITED STATES PATENTS 2,707,805 5/1955 Smith 18-57 2,960,725 11/1960 Lefevre l848 2,985,503 5/1961 Becker 18-54 3,095,606 7/1963 Scott 18-1 3,194,716 7/1965 Lefevre 264-285 ROBERT F. WHITE, Primary Examiner. R. R. KUCIA, Assistant Examiner. 

1. A METHOD FOR PREPARING FILAMENTARY MICROTAPES OF LABYRINTHIAN CROSS SECTION COMPRISING (1) THE PASSAGE OF A FLAT, FLEXIBLE TAPE OF AN ORGANIC THERMOPLASTIC POLYMER INTO A MOVING HEATED RESTRICTING MEANS OF NARROWER WIDTH THAN SAID TAPE WHILE SAID TAPE IS UNDER SUBSTANTIALLY NO LONGITUDIAL STRESS SAID RESTRICTING MEANS MOVING IN THE DIRECTION OF TRAVEL OF SAID TAPE AND AT ESSENTIALLY THE SAME PERIPHERAL SPEED AS THE LINEAR SPEED OF SAID TAPE SO THAT THE ONLY SHAPING FORCES EXERTED ON SAID TAPE ARE LATERAL FORCES, SAID TAPE BEING RETAINED IN SAID RESTRICTING MEANS UNTIL SAID TAPE HAS ATTAINED THE DESIRED CROSS-SECTIONAL CONFIGURATION, SAID HEATED RESTRICTING MEANS BEING OF DIFFERENT SHAPE THAN THE ULTIMATE CONFIGURATION OF THE PRODUCED FILAMENTARY MICROTAPE, SAID TAPE BEING PASSED INTO SAID HEATED RESTRICTING MEANS IN SUCH A MANNER THAT THE LONGITUDINAL AXIS OF SAID TAPE IS CENTERED IN SAID RESTRICTING MEANS, AND (2) REMOVING THE SHAPED TAPE FROM SAID RESTRICTING MEANS, FOLLOWED BY (3) COOLING THE SO-FORMED FILAMENTARY MICROTAPE. 